Semiconductor device and method of fabricating the same

ABSTRACT

A semiconductor device comprises a semiconductor chip having a plurality of electrodes formed in a first major surface thereof, a resin package sealing the semiconductor chip therein, a plurality leads electrically connected to the electrodes of the semiconductor chip and formed so as to extend inside and outside the resin package, and a support lead supporting the semiconductor chip at a part of a second major surface of the semiconductor chip opposite the first major surface. The semiconductor chip is bonded to the support lead with an adhesive tape.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a semiconductor device and, moreparticularly, to techniques effectively applicable to a semiconductordevice employing a lead frame of a coper-bearing metal.

[0002] Generally, a semiconductor device formed by sealing asemiconductor chip having a circuit system and a plurality electrodesformed on a circuit forming surface, i.e., a major surface, in a sealingresin package is fabricated by an assembling process using a lead frame.To put it concretely, a lead frame having a frame, support leads, a diepad (tab) supported by the support leads on the frame, and a pluralityof leads connected by tie bars (dam bars) is prepared. An Ag pasteprepared by mixing an adhesive paste, such as a thermosetting epoxyresin, and Ag powder is spread over the mounting surface of the die padof the lead frame in an adhesive resin film. A semiconductor chip havingelectrodes formed on a major surface thereof is mounted on the mountingsurface of the die pad coated with the adhesive resin film with a secondmajor surface of the semiconductor chip opposite the first major surfacein contact with the adhesive resin film formed on the die pad. Theadhesive resin film is hardened to fix the semiconductor chip to the diepad. The electrodes formed on the first major surface of semiconductorchip are connected electrically to the inner leads sections of the leadsof the lead frame by conductive bonding wires. The semiconductor chip,the inner leads, the die pad, the support leads and the bonding wiresare sealed in a resin package. Then, the outer leads are cut off theframe of the lead frame, the tie bars are cut, the outer leads areformed in predetermined shapes, and then the support leads are cut offthe frame of the lead frame.

[0003] Incidentally, it is an important problem with techniques relatingto a surface-mount semiconductor device, such as a quad flatpack package(QFP), to prevent cracks in the resin package, i.e., package cracks, dueto heat applied to the surface-mount semiconductor device for atemperature cycling test, i.e., an environmental test, or heat appliedto the same during reflow soldering when mounting the semiconductordevice on a wiring board. There are two known principal package crackingmechanisms that cause package cracks.

[0004] A first package cracking mechanism causes package cracks by theseparation of the die pad from the resin package and the evaporation andexpansion of moisture contained in the resin package by heat applied tothe semiconductor device for a temperature cycling test or reflowsoldering.

[0005] A second package cracking mechanism causes package cracks by theevaporation and expansion of moisture contained in the adhesive paste byheat applied to the semiconductor device for a temperature cycling testor reflow soldering, causing the separation of the semiconductor chipfrom the die pad.

[0006] A technique proposed to solve such a problem in, for example,Japanese Patent Laid-Open No. Sho 63-204753 uses a die pad having anarea smaller than that of a semiconductor chip to be mounted thereon.According to this prior art, the area of contact between a die pad and aresin package is small and hence it is possible to suppress thedevelopment of package cracks due to the evaporation and expansion ofthe moisture absorbed by the resin package. Furthermore, since the areaof an adhesive paste film sandwiched between the die pad and thesemiconductor chip is small, the development of package cracks due tothe evaporation and expansion of the moisture absorbed by the adhesivepaste film can be suppressed.

[0007] Another technique proposed to solve such a problem in, forexample, Japanese Patent Laid-open No. Hei 8-204107 uses an X-shaped diepad (cross tab) formed by two intersecting support leads to support asemiconductor chip at only a part of the surface thereof facing the diepad. This prior art also is able to suppress the development of packagecracks due to the evaporation and expansion of moisture absorbed by theresin package, and the development of package cracks due to theevaporation and expansion of moisture absorbed by the adhesive pastefilm.

SUMMARY OF THE INVENTION

[0008] When fabricating a semiconductor device, a Fe—Ni (iron-nickel)alloy lead frame is employed. Recently there has been a proliferation ofCu (copper) alloy lead frames. A semiconductor device employing a Cualloy lead frame, as compared with a semiconductor device employing anFe—Ni alloy lead frame, is excellent in heat dissipating performance andsignal transmission speed. However, since the Cu alloy lead frame has acoefficient of thermal expansion greater than that of the Fe—Ni alloylead frame, the semiconductor chip is liable to separate from the diepad of the Cu alloy lead frame and the reliability of the semiconductordevice employing a Cu alloy lead frame in preventing package cracks isdeteriorated.

[0009] It is effective, when a Cu alloy lead frame is employed, toreduce the area of the support leads in contact with a semiconductorchip by bonding the semiconductor chip to the support leads formed inthe least possible width. However, a new problem arises when the widthof the support leads is reduced.

[0010] The thickness of the adhesive resin film formed on the chipsupport parts of the support leads decreases with the decrease of thewidth of the support leads. Stress induced due to the difference incoefficient of thermal expansion between the support leads and thesemiconductor chip is absorbed by the adhesive resin film. The stressabsorbing ability of the adhesive resin film decreases with the decreaseof the thickness of the adhesive resin film. In a bonding process and amolding process in which the support leads and the semiconductor chipare heated, it is difficult to absorb the stress induced by thedifference in coefficient of thermal expansion between the support leadsand the semiconductor chip by the excessively thin adhesive resin film.Consequently, the support leads and the semiconductor chip are liable toseparate from each other and the semiconductor chip bonded to thesupport leads falls off the support leads, which reduces the yield ofthe semiconductor device assembling process.

[0011] Accordingly, it is an object of the present invention to providea technique capable of increasing the yield of a semiconductor deviceassembling process.

[0012] The above and other objects and novel features of the presentinvention will become apparent from the following description made inthe specification and the accompanying drawings.

[0013] Representative examples of the invention disclosed in the presentpatent application will briefly described below.

[0014] (1) A semiconductor device comprises a semiconductor chip havinga plurality of electrodes formed in a first major surface thereof; aresin package sealing the semiconductor chip therein; a plurality leadselectrically connected to the electrodes of the semiconductor chip andformed so as to extend inside and outside the resin package; and asupport lead supporting the semiconductor chip at a part of a secondmajor surface of the semiconductor chip opposite the first majorsurface; wherein the semiconductor chip is bonded to the support leadwith an adhesive tape.

[0015] (2) A semiconductor device comprises a square semiconductor chiphaving a plurality of electrodes formed in a first major surfacethereof; a square resin package sealing the semiconductor chip therein;a plurality of leads electrically connected to the electrodes of thesemiconductor chip and formed so as to extend inside and outside theresin package; and a support lead supporting the semiconductor chip at apart of a second major surface of the semiconductor chip opposite thefirst major surface, and extending through the two opposite corners ofthe semiconductor chip; wherein the semiconductor chip is bonded to thesupport lead with an adhesive tape.

[0016] (3) A semiconductor device comprises a square semiconductor chiphaving a plurality of electrodes formed in a first major surfacethereof; a square resin package sealing the semiconductor chip therein;a plurality leads electrically connected to the electrodes of thesemiconductor chip and formed so as to extend inside and outside theresin package; and a support lead supporting the semiconductor chip at apart of a second major surface of the semiconductor chip opposite thefirst major surface and extending across two opposite sides of thesemiconductor chip; wherein the semiconductor chip is bonded to thesupport lead with an adhesive tape.

[0017] (4) A semiconductor device comprises a square semiconductor chiphaving a plurality of electrodes formed in a first major surfacethereof; a square resin package sealing the semiconductor chip therein;a plurality leads electrically connected to the electrodes of thesemiconductor chip and formed so as to extend inside and outside theresin package; and a support lead supporting the semiconductor chip at apart of a second major surface of the semiconductor chip opposite thefirst major surface; wherein the resin package has a resin transfer partin a first corner thereof, the support lead extends from the firstcorner of the resin package toward a second corner of the same oppositethe first corner, and the semiconductor chip is bonded to the supportlead with an adhesive tape.

[0018] (5) A semiconductor device comprises a square semiconductor chiphaving a plurality of electrodes formed in a first major surfacethereof; a square resin package sealing the semiconductor chip therein;a plurality leads electrically connected to the electrodes of thesemiconductor chip and formed so as to extend inside and outside theresin package; and a support lead supporting the semiconductor chip at apart of a second major surface of the semiconductor chip opposite thefirst major surface; wherein the resin package has a first side providedin its middle part with a resin transfer part, the support lead extendson an imaginary line connecting the middle part of the first side of theresin package and a middle part of a second side of the same oppositethe first side, and the semiconductor chip is bonded to the support leadwith an adhesive tape.

[0019] According to the foregoing means, the adhesive tape can be formedin a great thickness regardless of the width of the support lead.Accordingly, the thickness of the adhesive tape can be determinedaccording to stress that may be induced due to the difference incoefficient of thermal expansion between the support lead and thesemiconductor chip. Consequently, the occurrence of a problem that thesemiconductor chip falls off the support lead after the die bondingprocess can be suppressed, whereby the yield of a semiconductor deviceassembling process can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a plan view of a semiconductor device in a firstembodiment according to the present invention, in which an upper part ofa resin package is removed;

[0021]FIG. 2 is a sectional view taken on line A-A in FIG. 1;

[0022]FIG. 3 is a sectional view taken on line B-B in FIG. 1;

[0023]FIG. 4 is a sectional view taken on line C-C in FIG. 1;

[0024]FIG. 5 is a perspective view of an essential part of thesemiconductor device;

[0025]FIG. 6 is a sectional view of the essential part shown in FIG. 3;

[0026]FIG. 7 is a plan view of a lead frame employed in fabricating thesemiconductor device;

[0027]FIG. 8 is a typical plan view of a resin film in an adhesive tapeforming process;

[0028]FIG. 9 is a typical sectional view taken on line D-D in FIG. 8;

[0029]FIG. 10 is a typical plan view of a resin film in an adhesive tapeforming process;

[0030]FIG. 11 is a plan view of assistance in explaining a method offabricating the semiconductor device;

[0031]FIG. 12 is a sectional view of assistance in explaining a methodof fabricating the semiconductor device;

[0032]FIG. 13 is a sectional view of assistance in explaining a methodof fabricating the semiconductor device;

[0033]FIG. 14 is a plan view of an essential part of a firstmodification of the resin film;

[0034]FIG. 15 is a plan view of an essential part of a secondmodification of the resin film;

[0035]FIG. 16 is a plan view of an essential part of a thirdmodification of the resin film;

[0036]FIG. 17 is a plan view of another lead frame to be employed infabricating the semiconductor device;

[0037]FIG. 18 is a plan view of another lead frame to be employed infabricating the semiconductor device;

[0038]FIG. 19 is a plan view of another lead frame to be employed infabricating the semiconductor device;

[0039]FIG. 20 is a plan view of another lead frame to be employed infabricating the semiconductor device;

[0040]FIG. 21 is a plan view of a semiconductor device in a secondembodiment according to the present invention, in which an upper part ofa resin package is removed;

[0041]FIG. 22 is a sectional view taken on line E-E in FIG. 21; and

[0042]FIG. 23 is a plan view of a lead frame to be employed infabricating the semiconductor device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] Preferred embodiments of the present invention will be describedwith reference to the accompanying drawings, in which parts having thesame functions are designated by the same reference characters and theduplicate description thereof will be omitted.

First Embodiment

[0044] A semiconductor device in a first embodiment according to thepresent invention is of a QFP (quad flatpack package) type having leadsarranged on the four sides thereof.

[0045] The construction of the semiconductor device will be describedwith reference to FIGS. 1 to 6. FIG. 1 is a plan view of thesemiconductor device in a first embodiment according to the presentinvention, in which an upper part of a resin package is removed, FIG. 2is a sectional view taken on line A-A in FIG. 1, FIG. 3 is a sectionalview taken on line B-B in FIG. 1, FIG. 4 is a sectional view taken online C-C in FIG. 1, FIG. 5 is a perspective view of an essential part ofthe semiconductor device;, and FIG. 6 is a sectional view of theessential part shown in FIG. 3.

[0046] Referring to FIGS. 1, 2, 3 and 4, the semiconductor device 1 inthe first embodiment is formed by mounting a semiconductor chip 10 onthe intersection 5 of a support lead 3 and an auxiliary lead 4, andsealing the semiconductor chip 10 in a resin package 13.

[0047] The semiconductor chip 10 has a square shape in a plane. Thesemiconductor chip 10 has the shape of, for example, a square whose sideis 9 mm. The semiconductor chip 10 comprises, as principal components, asemiconductor substrate of single crystal silicon, and wiring layersformed on the semiconductor substrate. This semiconductor chip 10 has acoefficient of thermal expansion on the order of 3×10⁻⁶ [1/°C].

[0048] A circuit system, such as a logic circuit system or a compositecircuit system consisting of a logic circuit system and a storagecircuit system, is formed on a circuit forming surface (first majorsurface) 10X of the semiconductor chip 10. The circuit system comprisessemiconductor elements formed on the semiconductor substrate and wiringlines formed on the semiconductor substrate and electrically connectingthe semiconductor elements. A plurality of electrodes (bonding pads) 11are formed on the circuit forming surface 10X of the semiconductor chip10 along the sides thereof. The plurality of electrodes 11 are formed inthe top one of the wiring layers of the semiconductor chip 10 and areelectrically connected by the wiring lines mainly to the componentsemiconductor elements of the circuit system. The plurality ofelectrodes 11 are formed by processing a metal film, such as aluminum(Al) or an aluminum alloy.

[0049] The resin package 13 is square in a plane. In this embodiment,the resin package 13 has the shape of a square whose side is 14 mm. Theresin package is formed of a resin, such as a biphenyl resin or anorthocresole novolac resin, containing a phenolic hardener, silicone anda filler to suppress stress induction. The resin package 13 has acoefficient of thermal expansion on the order of 13×10⁻⁶[1/°C].

[0050] The resin package 13 is formed by a transfer molding methodsuitable for mass production. The transfer molding method uses a moldinghaving a transfer pot, a runner, a transfer gate and a cavity, suppliesthe resin supplied from the pot to the runner, and transfers the resinthrough the transfer gate into the cavity to mold the resin package.

[0051] A plurality of leads 2 are arranged around the semiconductor chip10 along the sides of the resin package 13. Each of the plurality ofleads 2 extends inside and outside the resin package 13, and has aninner lead section 2A extending inside the resin package 13 and an outerlead section 2B extending outside the resin package 13.

[0052] The inner lead sections 2A of the plurality of leads 2 areconnected electrically to the electrodes 11 of the semiconductor chip 10by a conductive wires 12, respectively, and the outer lead sections 2Bof the same are formed in a shape suitable for surface-mounting, such asa gull-wing shape. For instance, the wires 12 are gold wires (Au wires).For instance, the wires 12 are connected to the inner lead sections 2Aby a bonding method using thermal compression bonding and ultrasonicbonding in combination.

[0053] The support lead 3, the auxiliary lead 4 and the wires 12 aresealed together with the semiconductor chip 10 in the resin package 13.

[0054] Referring to FIGS. 1 and 3, the support lead 3 extends between afirst corner 13A of the resin package 13 and a second corner 13B of thesame diagonally opposite the first corner 13A, and passes a first corner10A of the semiconductor chip 10 and a second corner 10B of the samediagonally opposite the first corner 10A; that is, the support lead 3extends on a diagonal connecting the first corner 13A and the secondcorner 13B of the resin package 13.

[0055] As shown in FIG. 3, the support lead 3 has lead sections 3A and3B. The lead section 3A is included in the thickness direction (verticaldirection) in a plane including the inner lead sections 2A of the leads2 shown in FIG. 2. The lead section 3B is included in the thicknessdirection (vertical direction) in a plane below the plane including theinner lead sections 2A of the leads 2 shown in FIG. 2.

[0056] As shown in FIG. 1 and 4, the auxiliary lead 4 extends between athird corner 13C of the resin package 13 and a fourth corner 13D of thesame diagonally opposite the third corner 13C, and passes a third corner10C of the semiconductor chip 10 and a fourth corner 10D of the samediagonally opposite the third corner 10C; that is, the auxiliary lead 4extends on a diagonal connecting the third corner 13C and the fourthcorner 13D of the resin package 13.

[0057] As shown in FIG. 4, the auxiliary lead 4 has lead sections 4A and4B. The lead section 4A is included in the thickness direction (verticaldirection) in a plane including the lead section 3A of the lead 3 shownin FIG. 3. The lead section 4B is included in the thickness direction(vertical direction) in the plane including the lead section 3A of thesupport lead 3 shown in FIG. 3.

[0058] As shown in FIG. 5, a gate break mark 13X is formed at the firstcorner 13A of the resin package 13. The gate break mark 13X is formedwhen a resin gate is broken off the resin package 13. The semiconductordevice 1 has a resin transfer part at the first corner 13A of the resinpackage 13.

[0059] As shown in FIG. 3, the semiconductor chip 10 is bonded to thelead section 3B of the support lead 3 with an adhesive tape 8. Theadhesive tape 8 extends longitudinally along the support lead 3. In thisembodiment, the adhesive tape 8 is stuck to the lead section 3B withparts thereof extending outside the semiconductor chip 10. The adhesivetape 8 is stuck to the lead section 3B of the support lead 3 so as to belongitudinally continuous along the support lead 3. Thus, thesemiconductor chip 10 is bonded to the lead section 3B of the supportlead 3 with the adhesive tape 8 longitudinally extending along thesupport lead 3.

[0060] The adhesive tape 8 comprises, for example, a resin base tape 8A,and adhesive layers 8B formed respectively on the major surfaces(opposite surfaces) of the base tape 8A. The resin base tape 8A isformed of a polyimide resin having a coefficient of thermal expansion onthe order of, for example, 2.5×10⁻⁵ [1/°C]. The adhesive layers 8B areformed of a thermoplastic poly(ether amide) or epoxy resin or athermosetting resin having a coefficient of thermal expansion on theorder of, for example, 5×10⁻⁵ [1/°C].

[0061] The thickness of the adhesive tape 8 is reduced slightly when thesemiconductor chip is bonded to the support lead 3 by thermalcompression bonding. The adhesive tape 8 is about 0.061 mm in thickness,the resin base tape 8A is about 0.025 mm in thickness and the adhesivelayers 8B are about 0.018 mm in thickness before the semiconductor chip10 is bonded to the support lead 3 by thermal compression bonding. Theadhesive tape 8 is about 0.05 mm in thickness after the semiconductorchip 10 has been bonded to the support lead 3 by thermal compressionbonding.

[0062] The thickness of the adhesive tape 8 may be increased regardlessof the width of the support lead 3. Accordingly, the thickness of theadhesive tape 8 can be determined according to stress that may beinduced due to the difference in coefficient of thermal expansionbetween the support lead 3 and the semiconductor chip 10.

[0063] The support lead 3 has a width in the range of, for example, 0.3to 0.5 mm. Therefore the support lead 3 supports the semiconductor chip10 at a part of a second major surface 10Y of the semiconductor chip 10opposite the first major surface 10X of the same.

[0064] Although the support lead 3 and the auxiliary lead 4 are regardedas a single lead in the foregoing description of the embodiment, theembodiment may be supposed to have two support leads 3 respectivelyextending in opposite directions from the intersection 5, and twoauxiliary leads 4 respectively extending in opposite directions from theintersection 5.

[0065] A lead frame employed in the semiconductor device 1 will bedescribed with reference to FIG. 7 showing a lead frame in a plan view.

[0066] Referring to FIG. 7, a lead frame LF1 has a square frame 7, aplurality of leads 2 for electrical connection, a support lead 3 forsupporting the semiconductor chip 10, and an auxiliary lead 4 forsupplementing the mechanical strength of the support lead 3. A resintransfer part is formed in a first corner 7A of the frame 7 of the leadframe LF1.

[0067] The leads 2 are divided into four lead groups, and the four leadgroups are arranged along the members of the frame 7, respectively. Eachof the leads 2 of each lead group has an inner lead section 2A extendinginside the resin package and an outer lead section 2B extending outsidethe resin package. The leads 2 of each lead group are connected by a tiebar 6, which prevents the leakage of the resin from the mold whenmolding the resin package in the mold. The outer lead sections 2B of theleads 2 of the lead groups are formed integrally with the frame 7.

[0068] The support lead 3 extends between a first corner 7A of the frame7 and a second corner 7B of the same diagonally opposite the firstcorner 7A. The support lead 3 has one end connected to the first corner7 a of the frame 7 and the other end connected to the tie bar 6. Thesupport lead 3 extends on a diagonal connecting the first corner 7A andthe second corner 7B of the frame 7 of the lead frame LF1.

[0069] The auxiliary lead 4 extends between a third corner 7C of theframe 7 and a fourth corner 7D of the same diagonally opposite the thirdcorner 7C. The auxiliary lead 4 has opposite ends connected to the tiebars 6. The auxiliary lead 4 extends on a diagonal connecting the thirdcorner 7C and the fourth corner 7D of the frame 7 of the lead frame LF1.

[0070] The support lead 3 and the auxiliary lead 4 intersect each otherand connected to each other in a central part of a region surrounded bythe frame 7. The support lead 3 and the auxiliary lead 4 are bent sothat the back surface, i.e., the lower surface, of the semiconductor 10as mounted on the support lead 3 lies in a plane below a plane includingthe upper connection surfaces of the leads 2.

[0071] The adhesive tape 8 is stuck to a chip mounting part of thesupport lead 3. The adhesive tape 8 is stuck to the lead section 3B ofthe support lead 3 so as to be longitudinally continuous along thesupport lead 3. The adhesive tape 8 has a width approximately equal tothat of the support lead 3.

[0072] The lead frame LF1 is formed of, for example, a copper alloyhaving a coefficient of thermal expansion on the order of 17×10⁻⁶[1/°C]. The lead frame LF1 is formed by subjecting a metal sheet to anetching process or a press working process to form the components of thelead frame LF1 including the leads 2, the support lead 3 and theauxiliary lead 4, shaping the support lead 3 and the auxiliary lead 4 bya press working process, and attaching the adhesive tape 8 to the chipmounting part of the support lead 3. Incidentally, a lead frame of anFe—Ni alloy containing, for example, 42% or 50% Ni has a coefficient ofthermal expansion on the order of 4.3×10⁻⁶ [1/°C.].

[0073] As shown in FIG. 8 (typical plan view of assistance in explaininga process of forming the adhesive tape) and FIG. 9 (a typical sectionalview taken on line D-D in FIG. 8), the adhesive tape 8 is formed bycutting an adhesive ribbon 15 of a predetermined width by using a jig16. Normally, the adhesive tape 8 is formed by cutting the adhesiveribbon 15 along a cutting line perpendicular to the long side (length)of the adhesive ribbon 15. As shown in FIG. 10 (a typical plan view ofassistance in explaining a process of forming the adhesive tape)adhesive tapes 8 of different lengths can be formed by cutting theadhesive ribbon 15 along oblique cutting lines inclined at acute anglesto the long side of the adhesive ribbon 15, respectively. An adhesivetape formed by cutting the adhesive ribbon 15 along an oblique cuttingline inclined at an acute angle to the long side of the adhesive ribbon15 has the shape of a parallelogram.

[0074] A method of fabricating the semiconductor device 1 will bedescribed hereinafter with reference to FIGS. 11 to 13. FIG. 11 is aplan view of the semiconductor device 1 at a stage of fabrication afterthe completion of a wire bonding process, and FIGS. 12 and 13 aresectional views of assistance in explaining a molding process. FIG. 12is a sectional view taken on line A-A in FIG. 1 and FIG. 13 is asectional view taken on line C-C in FIG. 1.

[0075] The lead frame LF1 shown in FIG. 7 is made. A mold 20 shown inFIGS. 12 and 13 is prepared. The mold 20 has an upper mold 20A and alower mold 20B. A cavity 21 is defined by the upper mold 20A and thelower mold 20B. The mold 20 is provided with a transfer gate 22 openinginto the cavity 21, a runner 23 connected to the gate 22, and a pot, notshown, connected to the runner 23.

[0076] The semiconductor chip 10 is bonded to the chip mounting part ofthe support lead 3 by the adhesive tape 8 by a thermal compressionbonding process. Although the support lead 3 and the semiconductor chip10 are heated in the thermal compression bonding process, thesemiconductor chip 10 will not fall off the support lead 3 because thethickness of the adhesive tape 8 is determined according to stress thatmay be induced due to the difference between the support lead 3 and thesemiconductor chip 10 in coefficient of thermal expansion.

[0077] The electrodes 11 of the semiconductor chip 10 are connectedelectrically to the inner lead sections 2A of the leads 2 by theconductive wires 12, respectively, by a wire bonding process usingthermal compression bonding and ultrasonic bonding in combination.Although the support lead 3 and the semiconductor chip 10 are heated inthe wire bonding process, the semiconductor chip 10 will not fall offthe support lead 3 because the thickness of the adhesive tape 8 isdetermined according to stress that may be induced due to the differencebetween the support lead 3 and the semiconductor chip 10 in coefficientof thermal expansion. These processes are illustrated in FIG. 11.

[0078] Referring to FIGS. 12 and 13, the frame 7 is placed between theupper mold 20A and the lower mold 20B of the mold 20 with the firstcorner 7A (resin transfer part) thereof located at a positioncorresponding to the transfer gate 22, and the semiconductor chip 10,the inner lead sections of the leads 2, the support lead 3, theauxiliary lead 4 and the wires 12 disposed in the cavity 22.

[0079] In a molding process, a resin is supplied from the pot and theresin is forced under pressure to flow through the runner 23 and thetransfer gate 22 into the cavity 21. Thus, the semiconductor chip 10,the inner lead sections of the leads 2, the support lead 3, theauxiliary lead 4 and the wires 12 are sealed in the resin. In themolding process, the variation of the vertical position of thesemiconductor chip 10 liable to be caused by the flow of the resinforced into the cavity 21 under pressure and flowing in the cavity 21can be suppressed because the semiconductor chip 10 is bonded to thesupport lead 3 extending away from the transfer gate 22. Since theauxiliary lead 4 is connected to the support lead 3, the mechanicalstrength of the support lead is supplemented by the auxiliary lead 4.Consequently, the variation of the vertical position of thesemiconductor chip 10 liable to be caused by the resin forced underpressure into the cavity 21 and flowing in the cavity 21 can besuppressed.

[0080] The lead frame LF1 is taken out of the mold 20, a resin gateconnected to the first corner 13A of the resin package 13 is removed,the tie bars 6 connecting the leads 2 are cut, the outer lead sections2B of the leads 2 are cut off the frame 7, the outer lead sections 2Bare formed in a shape suitable for surface-mounting, such as a gull-wingshape, and then the support lead 3 and the auxiliary lead 4 are cut offthe frame 7 to obtain the substantially completed semiconductor device 1shown in FIGS. 1 to 6.

[0081] The semiconductor device 1 is subjected to a temperature cyclingtest, and then the semiconductor device 1 is shipped as a product. Thesemiconductor device 1 shipped as a product is mounted on a wiringboard. The temperature cycling test repeats a test cycle 1000 times. Forinstance, the test cycle keeps the semiconductor device 1 at −55° C. for10 min and then keeps the same at 150° C. for 10 min. The semiconductordevice in accordance with the present invention was subjected to thetemperature cycling test. Any cracks were not formed in the resinpackage 13 of the semiconductor device 1.

[0082] The first embodiment exercises the following effects.

[0083] (1) The semiconductor chip 10 is bonded to the support lead 3 bythe adhesive tape 8. Accordingly, the thickness of the adhesive tape 8can be determined regardless of the width of the support lead 3 and canbe determined according to stress due to the difference in coefficientof thermal expansion between the support lead 3 and the semiconductorchip 10. Consequently, the occurrence of a problem that thesemiconductor chip 10 falls off the support lead 3 after the die bondingprocess can be suppressed, whereby the yield of the assembling processfor assembling the semiconductor device 1 can be improved.

[0084] Since the thickness of the adhesive tape 8 can be according tostress due to the difference in coefficient of thermal expansion betweenthe support lead 3 and the semiconductor chip 10, the yield of theassembling process for assembling the semiconductor device 1 employingthe lead frame LF1 of a Cu alloy can be improved.

[0085] (2) The semiconductor chip 10 is bonded to the support lead 3extending away from the resin transfer gate. Therefore, the variation ofthe vertical position of the semiconductor chip 10 due to the flow ofthe resin forced under pressure into and flowing in the cavity 21 can besuppressed. Accordingly, the development of defects, such as theexposure of the semiconductor chip 10 and the wires 12 outside the resinpackage 13, can be suppressed, which improves the yield of theassembling process for assembling the semiconductor device 1.

[0086] Since the possibility of the exposure of the semiconductor chip10 and the wires 12 outside the resin package 13 can be suppressed, theresin package 13 can be formed in a small thickness, which contributesto forming the semiconductor device 1 in a small thickness.

[0087] (3) The support lead 3 is connected to the auxiliary lead 4.Therefore, the mechanical strength of the support lead 3 is supplementedby the auxiliary lead 4 and the variation of the vertical position ofthe semiconductor chip 10 due to the flow of the resin forced underpressure into the cavity 21 can be suppressed.

[0088] (4) The semiconductor chip 10 is bonded to the support lead 3extending between the diagonally opposite first corner 10A and thesecond corner 10B. Therefore, as compared with a case where a centralpart of the semiconductor chip 10 is bonded, the vertical movement ofthe support lead 3 caused by the flow of the resin forced under pressureinto the cavity 21 can be suppressed.

[0089] (5) The support lead 3 is extended so as to pass the two oppositecorners 10A and 10B of the semiconductor chip 10, and the auxiliary lead4 is extended so as to pass the two opposite corners 10C and 10D. Sincethe support lead 3 and the auxiliary lead 4 do not extend in spacesbetween the semiconductor chip 10 and the tips of the leads 2, thepossibility of the contact of the wires 12 with the support lead 3 andthe auxiliary lead 4 can be avoided even if the wires 12 sag down. Thelonger the wires 12, the greater is the degree of sagging of the wires12.

[0090] Even if the external dimensions of the semiconductor chip 10 arereduced and the wires 12 sag down, the wires 12 do not come into contactwith the support lead 3 and the auxiliary lead 4 because the supportlead 3 and the auxiliary lead 4 do not extend in the spaces between thesemiconductor chip 10 and the tips of the leads 2. Therefore,semiconductor chips 10 of different dimensions can be supported on thesupport lead 3. Accordingly, lead frames capable of being mounted withsemiconductor chips 10 of different external dimensions can bestandardized.

[0091] In this embodiment, the width of the adhesive tape 8 is equal tothat of the support lead 3. The width W2 of the adhesive tape 8 may besmaller than the width W1 of the support lead 3 as shown in FIG. 14.

[0092] In this embodiment, the longitudinally continuous adhesive tape 8is attached to the support lead 3 so as to extend along the length ofthe support lead 3. Adhesive tapes 8 may be stuck to the support lead 3at intervals as shown in FIG. 15. The arrangement of the adhesive tapes8 at intervals as shown in FIG. 15 facilitates work for attaching theadhesive tape 8 to the support lead 3.

[0093] In this embodiment, the width of the adhesive tape 8 is equal tothat of the support lead 3. The width W2 of the adhesive tape 8 may begreater than the width W1 of the support lead 3.

[0094] A lead frame LF2 as shown in FIG. 17 may be employed infabricating a semiconductor device. The lead frame LF2 is not providedwith any component corresponding to the auxiliary lead 4. The effects ofa semiconductor device employing the lead frame LF2 are the same asthose of the semiconductor device 10 in the first embodiment. When theauxiliary lead 4 is omitted, the pitches of the leads 2 can beincreased, which is effective in reducing the possibility of contactbetween the wires that may be caused by the flow of the resin whenforming the resin package.

[0095] A lead frame LF3 as shown in FIG. 18 may be employed infabricating a semiconductor device. The lead frame LF3 is provided witha pad 25 wider than a support lead 3 and an auxiliary lead 4 and formedat the intersection of the support lead 3 and the auxiliary lead 4. Theeffects of a semiconductor device employing the lead frame LF3 are thesame as those of the semiconductor device 10 in the first embodiment.Since support frame 3 has an enhanced bending strength, the variation ofthe vertical position of the support lead 3 that may be caused by theflow of the resin when forming a resin package can further effectivelysuppressed.

[0096] A lead frame LF4 as shown in FIG. 19 may be employed infabricating a semiconductor device. The lead frame LF4 is provided witha pad 25 formed at the intersection of a support lead 3 and an auxiliarylead 4, and pads 26 extending from the pad 25 and wider than the supportlead 3 and the auxiliary lead 4. The effects of a semiconductor deviceemploying the lead frame LF4 are the same as those of the semiconductordevice 10 in the first embodiment.

[0097] A lead frame LF5 as shown in FIG. 20 may be employed infabricating a semiconductor device. The lead frame LF5 is provided witha pad 25 formed at the intersection of a support lead 3 and an auxiliarylead 4, and small pads 26 formed apart from the pad 25 in middlesections of the support lead 3 and the auxiliary lead 4. The effects ofa semiconductor device employing the lead frame LF5 are the same asthose of the semiconductor device 10 in the first embodiment.

[0098] A semiconductor device may employ a lead frame, not shown, havinga support lead 3 having a support section supporting the semiconductorchip 10 thereon and having a width greater than that of sections thereofnot corresponding to the semiconductor chip 10.

[0099] Although the semiconductor chip 10 is bonded to the support leadwith the adhesive tape in this embodiment, the semiconductor chip 10 maybe bonded to the support lead 3 with an adhesive layer, provided thatthe adhesive layer can be formed in a thickness not smaller than 30 μm.

Second Embodiment

[0100] A semiconductor device in a second embodiment according to thepresent invention is of a SOP (small outline package) type having leadsarranged on the two sides thereof.

[0101] The construction of the semiconductor device will be describedwith reference to FIGS. 21 and 22. FIG. 21 is a plan view of thesemiconductor device in a second embodiment according to the presentinvention, in which an upper part of a resin package is removed, andFIG. 22 is a sectional view taken on line E-E in FIG. 21.

[0102] Referring to FIGS. 21 and 22, the semiconductor device 30 in thesecond embodiment is formed by mounting a semiconductor chip 10 on achip mounting part of a support lead 3, and sealing the semiconductorchip 10 in a resin package 13.

[0103] The semiconductor chip 10 has a square shape in a plane and, inthis embodiment, the semiconductor chip 10 has, for example, arectangular shape. The semiconductor chip 10 has a circuit formingsurface 10X. A plurality of electrodes are formed on the circuit formingsurface 10X along the opposite long sides thereof. The resin package 13has a square shape in a plane and, in this embodiment, the resin package13 has, for example, a rectangular shape.

[0104] A plurality leads 2 are arranged outside the semiconductor chip10 along the opposite long sides of the resin package 13. Each of theplurality of leads 2 extends inside and outside the resin package 13,and has an inner lead section 2A extending inside the resin package 13and an outer lead section 2B extending outside the resin package 13.

[0105] The inner lead sections 2A of the plurality of leads 2 areconnected electrically to the electrodes 11 of the semiconductor chip 10by conductive wires 12, respectively, and the outer lead sections 2B ofthe same are formed in a shape suitable for surface-mounting, such as agull-wing shape. The support lead 3, the wires 12 and the semiconductorchip 10 are sealed in the resin package 13.

[0106] The support lead 3 extends on an imaginary line extending betweena middle part of a first side of the resin package 13 and a middle partof a second side 13Y of the same opposite the first side 13X. Thesupport lead 3 extends across a first side 10S of the back surface ofthe semiconductor chip 10 and a second side 10T of the same opposite thefirst side 10S.

[0107] A gate break mark, not shown, remains on the first side 13X ofthe resin package 13. The gate break mark is formed when a resin gateconnected to the resin package 13 is broken off. Therefore, thesemiconductor device 30 in this embodiment has a resin transfer part inthe middle part of the first side 13X of the resin package 13.

[0108] The semiconductor chip 10 is bonded to a lead section 3B of thesupport lead 3 with an adhesive tape 8. The adhesive tape 8 extendslongitudinally along the support lead 3. In this embodiment, theadhesive tape 8 is stuck to the lead section 3B with parts thereofextending outside the semiconductor chip 10. The adhesive tape 8 isstuck to the lead section 3B of the support lead 3 so as to belongitudinally continuous along the support lead 3. Thus, thesemiconductor chip 10 is bonded to the lead section 3B of the supportlead 3 with the adhesive tape 8 longitudinally extending along thesupport lead 3.

[0109] The thickness of the adhesive tape 8 may be increased regardlessof the width of the support lead 3. Accordingly, the thickness of theadhesive tape 8 can be determined according to stress that may beinduced due to the difference in coefficient of thermal expansionbetween the support lead 3 and the semiconductor chip 10.

[0110] The support lead 3 has a width of, for example, about 0.4 mm.Therefore the support lead 3 supports the semiconductor chip 10 at apart of a second major surface 10Y (back surface) of the semiconductorchip 10 opposite the first major surface 10X of the same.

[0111] A lead frame employed in fabricating the semiconductor device 30will be described with reference to FIG. 23 showing the lead frame in aplan view.

[0112] Referring to FIG. 23, a lead frame LF6 has a square frame 7, aplurality of leads 2 for electrical connection, and a support lead 3 forsupporting the semiconductor chip 10. A resin transfer part is formed ina first frame member 7X of the frame 7 of the lead frame LF6.

[0113] The plurality of leads 2 are divided into two lead groups, andthe two lead groups are disposed on the two opposite frame members ofthe frame 7, respectively. The leads 2 of each lead group are arrangedalong the along the frame member. Each of the leads 2 of each lead grouphas an inner lead section 2A extending inside the resin package and anouter lead section 2B extending outside the resin package. The leads 2of each lead group are connected by a tie bar 6, which prevents theleakage of the resin from the mold when molding the resin package in themold. The outer lead sections 2B of the leads 2 of the lead groups areformed integrally with the frame 7.

[0114] The support lead 3 extends between a middle part of the firstframe member 7X of the frame 7 and a middle part of a second framemember 7Y opposite the first frame member 7X. The support lead 3 has oneend connected to the first frame member 7X of the frame 7 and the otherend connected to the tie bar 6. The support lead 3 extends on a diagonalconnecting the first frame member 7X and the second frame member 7Y ofthe frame 7 of the lead frame LF6.

[0115] The adhesive tape 8 is stuck to the chip mounting part of thesupport lead 3. The adhesive tape 8 is stuck to the lead section 3B ofthe support lead 3 so as to be longitudinally continuous along thesupport lead 3. The adhesive tape 8 has a width approximately equal tothat of the support lead 3.

[0116] A method of fabricating the semiconductor device 30 will bedescribed hereinafter. The lead frame LF6 shown in FIG. 23 is made. Amold is prepared. The mold has an upper mold and a lower mold. A cavityis defined by the upper and the lower mold. The mold is provided with atransfer gate opening into the cavity, a runner connected to thetransfer gate, and a pot connected to the runner.

[0117] The semiconductor chip 10 is bonded to the chip mounting part ofthe support lead 3 by the adhesive tape 8 by a thermal compressionbonding process. Although the support lead 3 and the semiconductor chip10 are heated in the thermal compression bonding process, thesemiconductor chip 10 will not fall off the support lead 3 because thethickness of the adhesive tape 8 is determined according to stress thatmay be induced due to the difference between the support lead 3 and thesemiconductor chip 10 in coefficient of thermal expansion.

[0118] The electrodes 11 of the semiconductor chip 10 are connectedelectrically to the inner lead sections 2A of the leads 2 by theconductive wires 12, respectively, by a wire bonding process usingthermal compression bonding and ultrasonic bonding in combination.Although the support lead 3 and the semiconductor chip 10 are heated inthe wire bonding process, the semiconductor chip 10 will not fall offthe support lead 3 because the thickness of the adhesive tape 8 isdetermined according to stress that may be induced due to the differencebetween the support lead 3 and the semiconductor chip 10 in coefficientof thermal expansion.

[0119] The frame 7 is placed between the upper and the lower mold of themold with the resin transfer part thereof located at a positioncorresponding to the transfer gate, and the semiconductor chip 10, theinner lead sections of the leads 2, the support lead 3 and the wires 12disposed in the cavity.

[0120] In a molding process, a resin is supplied from the pot and theresin is forced under pressure to flow through the runner and thetransfer gate into the cavity. Thus, the semiconductor chip 10, theinner lead sections of the leads 2, the support lead 3 and the wires 12are sealed in the resin. In the molding process, the variation of thevertical position of the semiconductor chip 10 liable to be caused bythe flow of the resin forced into the cavity under pressure and flowingin the cavity can be suppressed because the semiconductor chip 10 isbonded to the support lead 3 extending away from the transfer gate.

[0121] The lead frame LF6 is taken out of the mold, a resin gateconnected to the first side 13X of the resin package 13 is removed, thetie bars 6 connecting the leads 2 are cut, the outer lead sections 2B ofthe leads 2 are cut off the frame 7, the outer lead sections 2B areformed in a shape suitable for surface-mounting, such as a gull-wingshape, and then the support lead 3 is cut off the frame 7 to obtain thesubstantially completed semiconductor device 30 shown in FIGS. 21 and22. The second embodiment has effects similar to those of the firstembodiment.

[0122] Although the invention has been described in the preferredembodiments thereof, the embodiments described herein are notrestrictive and many changes and variations may be made therein withoutdeparting from the scope of the present invention.

[0123] For example, the present invention is applicable to semiconductordevices of a SIP (single in-line package) type and a ZIP (zigzag in-linepackage) type having leads arranged in a single row.

[0124] The present invention is applicable also to semiconductor devicesof a SOJ (small out-line J-leaded package) type and a TSOP (thin smallout-line package) type having leads arranged in two rows.

[0125] The present invention is applicable also to semiconductor devicesof a QFJ (quad flat pack J-leaded package) type having leads arranged infour rows.

What is claimed is:
 1. A semiconductor device comprising: asemiconductor chip having a plurality of electrodes formed in a firstmajor surface thereof; a resin package sealing the semiconductor chiptherein; a plurality leads electrically connected to the electrodes ofthe semiconductor chip and formed so as to extend inside and outside theresin package; and a support lead supporting the semiconductor chip at apart of a second major surface of the semiconductor chip opposite thefirst major surface; wherein the semiconductor chip is bonded to thesupport lead with an adhesive tape.
 2. A semiconductor devicecomprising: a square semiconductor chip having a plurality of electrodesformed in a first major surface thereof; a square resin package sealingthe semiconductor chip therein; a plurality of leads electricallyconnected to the electrodes of the semiconductor chip and formed so asto extend inside and outside the resin package; and a support leadsupporting the semiconductor chip at a part of a second major surface ofthe semiconductor chip opposite the first major surface, and extendingthrough the two opposite corners of the semiconductor chip; wherein thesemiconductor chip is bonded to the support lead with an adhesive tape.3. A semiconductor device comprising: a square semiconductor chip havinga plurality of electrodes formed in a first major surface thereof; asquare resin package sealing the semiconductor chip therein; a pluralityleads electrically connected to the electrodes of the semiconductor chipand formed so as to extend inside and outside the resin package; and asupport lead supporting the semiconductor chip at a part of a secondmajor surface of the semiconductor chip opposite the first major surfaceand extending across two opposite sides of the semiconductor chip;wherein the semiconductor chip is bonded to the support lead with anadhesive tape.
 4. A semiconductor device comprising: a squaresemiconductor chip having a plurality of electrodes formed in a firstmajor surface thereof; a square resin package sealing the semiconductorchip therein; a plurality leads electrically connected to the electrodesof the semiconductor chip and formed so as to extend inside and outsidethe resin package; and a support lead supporting the semiconductor chipat a part of a second major surface of the semiconductor chip oppositethe first major surface; wherein the resin package has a resin transferpart in a first corner thereof, the support lead extends from the firstcorner of the resin package toward a second corner of the same oppositethe first corner, and the semiconductor chip is bonded to the supportlead with an adhesive tape.
 5. A semiconductor device comprising: asquare semiconductor chip having a plurality of electrodes formed in afirst major surface thereof; a square resin package sealing thesemiconductor chip therein; a plurality leads electrically connected tothe electrodes of the semiconductor chip and formed so as to extendinside and outside the resin package; and a support lead supporting thesemiconductor chip at a part of a second major surface of thesemiconductor chip opposite the first major surface; wherein the resinpackage has a first side provided in its middle part with a resintransfer part, the support lead extends on an imaginary line connectingthe middle part of the first side of the resin package and a middle partof a second side of the same opposite the first side, and thesemiconductor chip is bonded to the support lead with an adhesive tape.6. The semiconductor device according to claim 1, wherein the adhesivetape has a resin base member, and adhesive layers formed respectively onthe opposite major surfaces of the resin base member.
 7. Thesemiconductor device according to claim 1, wherein the adhesive tapeextends longitudinally along the length of the support lead.
 8. Thesemiconductor device according to claim 1, wherein the adhesive tape isstuck to the support lead so that part thereof extends outside thesemiconductor chip.
 9. The semiconductor device according to claim 1,wherein the adhesive tape is stuck to the support lead so as to extendlongitudinally continuously along the length of the support lead. 10.The semiconductor device according to claim 1, wherein the adhesive tapeis stuck to the support lead at intervals along the length of thesupport lead.
 11. The semiconductor device according to claim 1, whereinthe support lead is made of copper or a copper alloy.
 12. A method offabricating a semiconductor device comprising a semiconductor chiphaving a plurality of electrodes formed in a first major surfacethereof, a resin package sealing the semiconductor chip therein, aplurality leads electrically connected to the electrodes of thesemiconductor chip and formed so as to extend inside and outside theresin package, and a support lead supporting the semiconductor chip at apart of a second major surface of the semiconductor chip opposite thefirst major surface; wherein the semiconductor chip is bonded to thesupport lead by an adhesive tape.
 13. A method of fabricating asemiconductor device, said method comprising the steps of: preparing alead frame having a frame of a square shape in a plane, a plurality ofleads supported on the frame, a support lead supported on the frame, andan adhesive tape stuck to the support lead, said frame provided with aresin transfer part in a first corner thereof, each of said leads havingan inner lead section and an outer lead section, said support leadextending between the first corner of the frame and a second corner ofthe same opposite the first corner, and a mold comprising an upper moldand a lower mold, and having a cavity defined by the upper and the lowermold, and a resin transfer gate opening into the cavity; adhesivelybonding the semiconductor chip to the support lead by the adhesive tape;electrically connecting the Electrodes of the semiconductor chip to theinner lead sections of the leads by conductive wires, respectively; anddisposing the lead frame between the upper and the lower mold of themold so that the resin transfer part of the frame coincides with theresin transfer gate, injecting a resin through the resin transfer gateinto the cavity to seal the semiconductor chip, the inner lead sectionsof the leads, the support lead and the wires in the resin.
 14. A methodof fabricating a semiconductor device, said method comprising the stepsof: preparing a lead frame having a frame of a square shape in a plane,a plurality of leads supported on the frame, a support lead supported onthe frame, and an adhesive tape stuck to the support lead, said frameprovided with a resin transfer part in a first frame member thereof,each of said leads having an inner lead section and an outer leadsection, said support lead extending on an imaginary line extendingbetween a middle part of the first frame member of the frame and amiddle part of a second member of the same opposite the first framemember, and a mold comprising an upper mold and a lower mold, and havinga cavity defined by the upper and the lower mold, and a resin transfergate opening into the cavity; adhesively bonding the semiconductor chipto the support lead by the adhesive tape; electrically connecting theelectrodes of the semiconductor chip to the inner lead sections of theleads by conductive wires, respectively; and disposing the lead framebetween the upper and the lower mold of the mold so that the resintransfer part of the frame coincides with the resin transfer gate,injecting a resin through the resin transfer gate into the cavity toseal the semiconductor chip, the inner lead sections of the leads, thesupport lead and the wires in the resin.
 15. A method of fabricating thesemiconductor device according to claim 11, wherein the adhesive tapehas a resin base member, and adhesive layers formed respectively on theopposite major surfaces of the resin base member.
 16. The method offabricating the semiconductor device according to claim 11, wherein theadhesive tape extends longitudinally along the length of the supportlead.
 17. The method of fabricating the semiconductor device accordingto claim 11, wherein the adhesive tape is stuck to the support lead soas to extend longitudinally continuously along the length of the supportlead.
 18. The method of fabricating the semiconductor device accordingto claim 11, wherein the adhesive tape is stuck to the support lead atintervals along the length of the support lead.
 19. The method offabricating the semiconductor device according to claim 11, wherein thelead frame is made of copper or a copper alloy.